1. Field of the Invention
The present invention relates to a semiconductor light emitting device, and more particularly, to a semiconductor light emitting device having a current blocking layer.
2. Description of the Related Art
A semiconductor light emitting device has strengths as a light source in terms of high output, excellent light efficiency and reliability thereof, and therefore, research thereinto and development thereof to allow for use as a high output and a high efficiency light source in a backlight in a lighting device or a display device has been actively undertaken.
In general, a semiconductor light emitting device includes an active layer able to emit light by the recombination of electrons and holes between and a p-type semiconductor layer and an n-type semiconductor layer. Such semiconductor light emitting devices may be classified according to a position in which an electrode is located to form a semiconductor layer or according to a current path, and although they are not particularly limited, the classification thereof may be determined depending upon whether or not electrical conductivity exists in a substrate mainly used for a semiconductor light emitting device.
For example, when a substrate having electrical insulation is used, mesa etching to form a first electrode connected to a first conductive semiconductor layer may be required. That is, portions of the second conductive semiconductor layer and an active layer may be partially removed to expose a portion in a first conductive semiconductor layer region, and the first electrode is formed on an exposed top surface of the first conductive semiconductor layer.
In the above-mentioned electrode structure, a light emitting area may be reduced during a mesa etching process and may be formed in a direction perpendicular to that of current flow, and thus it may be difficult to promote uniform current distribution across an overall area, which may cause a reduction in light emission efficiency.
Meanwhile, when a conductive substrate is used, the conductive substrate may be used as a side electrode. In this semiconductor light emitting device structure, there is little light loss in a light emitting area as compared to the former structure, and a uniform current flow may be comparatively secured therein, whereby light emission efficiency can be enhanced.
However, in this case, an electrode, mainly an n-side electrode, positioned on the light emission surface should also be formed to have a reduced size in order to smoothly emit light, but in this case, a driving voltage increases, and furthermore, current spreading effects may be deteriorated, whereby a substantial region of an actual active layer may not actually be utilized as an effective light emitting region.
Therefore, in order to increase light emission efficiency in a light emitting diode (LED), research into significantly increasing current spreading effects has become a significant issue and has been urgently required in light emitting devices in order to obtain a high light output, particularly implemented through a large area thereof.